How to Do a Cube Root on a TI-84

Square roots get their own key on a TI-84, but cube roots don’t — which is why people often go looking in the wrong menu the first time they need one.

The shortcut

The cube root has its own dedicated shortcut: MATH → 4: ³√(. Type ³√(8) and you get 2, since 2³ = 8. It’s listed separately from the general nth-root tool precisely because cube roots come up often enough to deserve their own entry.

The general case: nth root

For any other root — a 4th root, a 5th root — you use MATH → 5: ˣ√ instead, typed as n ˣ√ value (the root index first). A cube root is really just the special case 3 ˣ√ value, which is exactly why the dedicated ³√( shortcut exists: it saves you from typing the 3 and the root symbol separately every time.

Worked example

³√(-27) = -3, since -3³ = -27 — unlike a square root, a cube root is defined for negative numbers too, because an odd power of a negative number stays negative.

Try it yourself

On the TI-84 Calculator, type cbrt( directly into the expression line — for example, cbrt(-27) — the same way you’d type sqrt(. It’s listed in the Functions tab reference alongside sqrt(x) for quick lookup if you forget the exact syntax.